WP Tavern was running on PHP 5.4.28 and we upgraded it to PHP 7 today. Here is a speed comparison.

PHP 5.4 Full Load PHP 5.4 First Byte PHP 7 Full Load PHP 7 First Byte

9.8 2.88 7.2 1.21

The numbers for PHP7 are definitely an improvement and the first thing we noticed is how much faster the WordPress backend loads. We should have upgraded sooner!